3 replies to this topic

[Settler]

Could somebody help me with finding Antoine coefficients and vapor pressure for some organic compounds? By help i mean the exact coefficient or title of a book or link or article, simply anything that will help me. The main problem is that i have checked this page, a few books (like "The properties of gases and liquids" by Poling and a few more). This knowledge is needed for my engineering degree exam because my subject is to analyse the process of organic compounds distillation from a wort. I can't find vapor pressures for: α-Ketoglutaric acid, amber acid and arabitol. Antoine coefficients for those three and for lactic acid, erythritol, mannitol, fumaric acid, citric acid and glucose are in my area of interests. My lecturers couldn't help me even if physical properties are on their field of work.

I hope that someone will be able to help me.
Thank you in advance.

[katmar]

I have not worked with most of the compounds that you have listed here, but I know the more common ones like fumaric acid, citric acid and glucose. All 3 of these have melting points well in excess of 100 deg C and do not have normal boiling points - they will decompose or burn before they boil. This means that their vapor pressures are exceedingly low and can safely be neglected in distillation calculations.

Check the melting and boiling points of the others and you may find that you can neglect them as well. For those that are likely to have appreciable vapor pressures you may have to use an estimation method based on group contributions as described in the book by Poling.

In distilling a normal wort you will have your hands full trying to deal with the usual compounds like methanol, ethanol, propanol, butanol, pentanol, acetic acid and a variety of aldehydes. You don't want to further complicate the issue with components that really have no impact on the distillation results.

[Settler]

Thank you for very fast reply, the estimation method sounds very tempting.
When it comes to decomposition, I know that they do decompose but i'm supposed to analyse it in normal and lowered pressure. Clapeyron equation should be very helpful here. That's why i need those coefficients. My wort is based on glucose, glycerol and waste glycerol if that means anything. If i won't make it through distillation then I start thinking about different method.

[katmar]

That is correct - those components will never influence the distillation. They will go out with the bottoms of the first column and never enter the vapor phase. They will also not decompose under the conditions found in a distillery.